This invention relates to tools for installing generally tubular sheathing, such as split ringed sheathing, around elongated items, such as bundles of electric cables. Nowadays, many types of tool are known for the application of such sheathing.
One type of tool consists of a simple shuttle with a guide head which makes it possible to open the sheathing and an orifice into which are passed the cables to be sheathed. This tool, however, is limited to use with cables of which one extremity at least is free. It does not therefore apply to cables which are already laid and which have their two extremities fixed, and it does not, moreover, allow passage of the sheath over branches from the bundle of strands. Bridging over of fittings or connectors presupposes making them pass into and through the orifice of the shuttle, which consequently then has to be oversized to accommodate them. Such a tool type is shown in JP-A-5742007 (Patent Abstracts of Japan Vol 6. No 112). A similar tool is shown in U.S. Pat. No. 4,593,442 but wherein the guide head, which extends through a longitudinal slit of the tubing, is formed in two separable grooved parts which co-operate to define an enclosed feed duct; the ability to split the guide head permits on the tool to be applied to, or separated from, a partially sheathed item without access to the end of the item, but such tool assembly/disassembly is not a trivial operation and not suited to a frequently necessary production step.
A second known type of tool consists of an articulated gripping jaw made up of two symmetrical parts held against each other by a spring. In the open position, the jaws allow the introduction of a bundle of cables to be sheathed into a duct. When in the dosed position, two integral protuberances, one on each of the respective halves of the jaws which together form a head for expanding or otherwise opening the sheathing to be installed. The tool is then dragged along the bundle of cables to be sheathed. Any cable branch, joint or connector encountered interrupts the sheathing operation. The device must then be opened and the cables must be removed from it. Accommodate for connectors or fittings is to made by expanding and/or opening the sheathing manually, with the fingers, in order to carry out the sheathing operation. The tool is then re-introduced for sheathing the bundle as far as the next obstacle. It is apparent that this technique is hardly efficient if numerous branches or numerous connectors are present in the network to be sheathed. Moreover, this technique brings risk of injury to the user on the edges of a non-fabric split sheath, such as a plastic ringed sheath, or of pinching electric wires of small diameter by the jaws of the tool.
A third known tool consists of a handle, a guide head which opens or expands the split sheath and a semi-circular bar located at 60xc2x0 to the head in the direction the tool moves forward. Traction of the tool then allows the introduction of cables into the sheathing. This arrangement brings the main inconvenience that the wires are subject to little guidance, can easily come out of the sheathing.
The present invention thus intends to remedy these inconveniences by producing a sheathing tool which is more convenient and more efficient in use, and which even permits, for example, clearing obstacles like branches off the bundle of cables and which can be used on already laid networks where the wires do not have a free end.
According to a second aspect of the invention, this tool is made robust by assembling it in a single integral block, without movable parts.
The ergonomics of the tool and ease and rapidity of use constitute a third objective of the present invention.
In like manner, the possibility of mechanising the application of the sheathing bundle of cables constitutes a major advantage of the invention.
The tool of this invention similarly improves safety in use for its user by preventing the user from touching the possibly sharp edges of the sheath to be fitted, and this constitutes an additional advantage of the invention.
Finally, its suitability for different types of sheaths, such as split ringed plastic sheathing, textiles etc, constitutes another advantage of the device according to the invention.
According to the present invention, a device for inserting elongated items into a sheath which is slit longitudinally and has free edges extending approximately parallel to its axis, said device being capable of being moved in relation to the sheath in a direction generally parallel to said sheath, said device having a head comprising opening means for the sheath and which has, on the one hand, a first passage for the sheath during its relative movement in relation to the tool, and also a second passage for the elongated items in order to introduce them between the separated edges of the sheath, said second passage being located obliquely in relation to the axis of the head, characterised in that said head has a lateral passage which communicates with the second passage for the elongated items and which forms an angle with the axis of the head which is different from that formed between the axis of the second passage for the elongated items and the axis of the head, said lateral passage being adapted for the introduction or extraction of one or more elongated items during the movement of the sheath relative to the head of the tool.
It will be appreciated that the device of this invention is thus a device for the insertion of cables into a split sheath, either one of which is already split, or one which is split immediately prior to the sheathing operation; it is movable relative to the sheath, and it has a head which ensures the opening/expansion of the sheath; it features a channel for the cables to introduce them between the separated edges of the sheath, the latter channel being located obliquely in relation to the sheath and is characterised in that is has a lateral passage communicating with the channel for the cables, said lateral passage being disposed at an angle to this channel.
It will be understood that this arrangement also allows for the tool to be used on cables where the two extremities are fixed, and similarly to ensure the clearance of branches of cables without having to separate the tool from the sheath or from the cables to be sheathed. It therefore provides a good answer to problems caused by known tools constituting the state of the art. Such an implementation guarantees that cables which have a tendency because of their own mechanical structure to remain grouped around their axis, will not spontaneously come out of the tool during an insertion/sheathing operation. Consequently, their extraction or introduction (via the lateral passage) will remain very simple for the user.
According to one preferred embodiment, the tool is further characterised in that part at least of the surface of the passage for the elongated items, and/or of the passage for the sheath, and/or of the lateral passage, has a surface layer of a material with a reduced coefficient of friction.
According to a further feature of the invention, a preferred method of using a tool according to the invention comprises the steps of:
(a) presenting the tool to elongated items to be sheathed so as to introduce the latter to the second passage,
(b) introducing the sheath to opening means via the first passage,
(c) dragging the tool relative to the sheath and elongated items until the latter are enclosed by the sheath,
(d) during step (c) introducing new or additional elongated items via the lateral passage, or extracting one or more items via said lateral passage.
It will be understood that these steps are compatible with mechanisation of the placing of the sheath onto the cables by dividing the process into at least three steps; namely bringing the items to the tool, putting the tool in position and then using the tool. As will be understood, only a tool which makes it possible to ensure that neither the cables nor the sheath need leave their paths is compatible with automation of the sheathing in this way. This is an important advantage with regard to previous known systems.
The reduction in friction obtained by treating the surface of the parts of the tool exposed to sliding friction, and preferably by having a small angle between the axis of the cables and the axis of the sheath contributes to the particularly advantageous implementation of the invention in automated form.
According to one especially advantageous method of operation, the process of sheathing furthermore includes the following stages:
clearance of joints or other obstacles disposed lengthwise of an elongated item, by extraction from the tool via the lateral passage, the elongated item(s) involved in the joint or obstacle followed by and continuation of the movement of the tool;
introduction into a group of elongated items a further elongated item which has to be inserted into the sheath, by introducing said further elongated item into the group via the lateral passage of the tool followed by continued dragging of the tool relative to the sheath and the elongated items.